Luciano José Quintão Teixeira

Microbial modeling of thermal resistance of Alicyclobacillus acidoterrestris CRA7152 spores in concentrated orange juice with nisin addition

Estudou-se o efeito da nisina na inativacao termica dos esporos de Alicyclobacillus acidoterrestris CRA 7152 em suco de laranja concentrado (64 oBrix). Foram avaliadas as concentracoes de 0, 50, 75 e 100 UI de nisina/ml de suco nas temperaturas de 92, 95, 98 e 102 oC. Foi utilizado o modelo polinomial quadratico para analisar os efeitos dos fatores e suas interacoes. A contagem dos esporos sobreviventes foi feita atraves de plaqueamento em meio K (pH = 3,7). De acordo com os resultados obtidos encontrouse um valor de D sem adicao de nisina de 25,5; 12,9; 6,1 e 2,3 min para as temperaturas de 92, 95, 98 e 102 oC respectivamente. Quando a nisina foi adicionada ao suco observouse uma queda na resistencia termica em funcao do aumento da concentracao de nisina para os mesmos valores de temperatura. Ao utilizar as concentracoes de 30, 50, 75 e 150 IU/ml a 95 oC, o valor de D obtido foi de 12,34; 11,38; 10,49; 9,49; e 9,42 min respectivamente demonstrando que a adicao de nisina provoca um decrescimo de ate 27 % no valor de D. O modelo polinomial de segunda ordem ajustado com r2 = 0,995 mostrou que a resistencia do microorganismo foi afetada pela temperatura seguida da concentracao de nisina. A adicao de nisina e, portanto, uma alternativa para reduzir o rigor do tratamento termico em A. acidoterrestris CRA 7152.The nisin effect on thermal death of Alicyclobacillus acidoterrestris CRA 7152 spores in concentrated orange juice (64oBrix) was studied. Concentrations of 0, 50, 75 and 100 IU of nisin/ml juice, at temperatures of 92, 95, 98 and 102oC were evaluated. The quadratic polynomial model was used to analyze the effects of the factors and their interaction. Verification of surviving spores was carried out through plating in K medium (pH 3.7). The results showed that the D values without nisin addition were 25.5, 12.9, 6.1 and 2.3 min for 92, 95, 98 and 102oC respectively. With addition of nisin into the juice there was a drop of heat resistance as the concentration was increased at a same temperature. With 30, 50, 75, 100 and 150 IU/ml at 95oC, the D values were 12.34, 11.38, 10.49, 9.49 and 9.42 min respectively, showing that a decrease in the D value up to 27% can be obtained. The second order polynomial model established with r2 = 0.995 showed that the microorganism resistance was affected by the action of temperature followed by the nisin concentration. Nisin therefore is an alternative for reducing the rigor of the A. acidoterrestris CRA 7152 thermal treatment.

Campo elétrico pulsado

Pulsed electric fields of high intensity (HIPEF) is a non-thermal food conservation to replace traditional thermal pasteurization. Compared to thermal processing, the HIPEF as well as being effective in removing microorganisms and inactivate enzymes also minimize the loss of flavor, color, texture, nutrients and labile components of food. The aim of this work was to gather bibliographic data current HIPEF on the subject, covering: experimental setup, effects of dielectric breakdown of food, effect on microorganisms, enzymes and constituents of food. The data found in the literature indicate treatment of HIPEF as a promising alternative for food conservation and it could be used as a single technology or in addition to thermal processing.

Revalidação do método titulométrico para determinação do ácido ascórbico

Validation of the method for determination of ascorbic acid in lemon by titration The present study aimed to revalidate the method for determination of ascorbic acid by titration to be applied in the laboratory of Food Chemistry Centre of Agricultural Sciences, Federal University of Espirito Santo. The revalidation process was carried out by evaluating parameters such as linearity , precision (repeatability), accuracy (recovery test) and detection limits, considering the acceptability criteria determined. The level of significance in hypothesis testing was 5%. Analyses included simple linear correlation coef ficient (r), coefficient of variation (CV) and regression analysis. The data were analyzed using the software Statistica 7.0. The quantitative method by titration of ascorbic acid was revalidated and evaluated in samples of ascorbic acid and lemon juice. It was found that the same complies with the limits established by regulatory agencies. The methods presented linear, repetitive and high recovery, with a maximum value of 98% and a minimum of 94.82% and a detection limit of 0.025 mg ml -1 in the lemon juice.

PESTICIDE RESIDUES IN CONVENTIONALLY AND ORGANICALLY GROWN TOMATOES IN ESPÍRITO SANTO (BRAZIL)

The aim of this study was to investigate the presence of acephate, carbaryl, carbendazim, chlorpyrifos, dichlorvos, fenpropathrin, methamidophos and permethrin in conventionally and organically grown tomatoes from Espirito Santo, Brazil, between May 2012 and April 2013. QuEChERS sample preparation was used and analysis was performed by LC-MS/MS and GC-MS. The method validation showed good linearity (R > 0.99), precision (RSD < 13%) and accuracy (89 - 123%), and the limits of quantification were below 0.01 mg kg-1 for all pesticides. The pesticides acephate, carbaryl (0.23 mg kg-1; exceeding maximum residue levels), carbendazim, chlorpyriphos, dichlorvos, fenpropathrin (0.41 mg kg-1; exceeding maximum residue levels), methamidophos and permethrin (0.51 mg kg-1, exceeding maximum residue levels) were found in conventional tomatoes. In organic tomatoes, only one sample exhibited the presence of permethrin (0.21 mg kg-1). Considering that the pesticides found are toxic and carcinogenic, and given the high incidence of irregularities, it is important to implement government actions to ensure consumer safety.

OTIMIZAÇÃO DO PROCESSO DE SECAGEM EM LEITO DE ESPUMA DE EXTRATO DE CAFÉ

During the processing of soluble coffee occur losses of aromas, besides degradation and formation of undesirable compounds. Foam mat drying uses low temperatures, resulting in a high-quality product and occur less losses of volatile compounds and nutrients during the process. The objective of this work was to optimize the concentrations of emustab® and whey powder in the foam mat drying process of coffee extract, as well as to evaluate the effect of the temperature on drying kinetics. A Central Composite Rotatable Design (CCRD) was used, with the concentrations of the two agents ranging from 0 to 8%. Then, drying was performed at five temperatures (50, 55, 60, 65 and 70 ° C) and their kinetics were adjusted by comparing the Page, Henderson and Pabis and Exponential models by a non-linear

Cinética de secagem de acerola em leito de espuma e ajuste de modelos matemáticos

Acerola (Malpighia emarginata DC) is a fruit rich in nutrients, especially vitamin C, but the in natura fruit is highly perishable and hence processing of the acerola pulp becomes indispensable. The aim of this paper was to study the foam mat drying process of acerola pulp to evaluate the effect of temperature on the drying kinetics of the pulp and fit mathematical models in order to describe the operation. The experiment was carried out with three repetitions. The foam was prepared with 250 mL of the pulp plus 4% of foaming agent and spread evenly in stainless steel trays. The selected drying air temperatures were 50 °C, 55 °C, 60 °C, 65 °C and 70 °C. The moisture ratios were then calculated and the Page, Henderson and Pabis and Lewis mathematical models fitted for each temperature. The Page model showed the highest determination coefficient (> 0.99) and lowest standard error for the regression at all temperatures (<0.03). The proposed generalized model presented a determination coefficient of 0.9933. The Page model and the generalized model were adequate to describe the drying process of the acerola pulp. The moisture contents of the dehydrated products were in accordance with the values established by Brazilian law.